Boyhood star Ellar Coltrane says it was 'confronting' to watch himself grow up in Richard Linklater's 12-year film

"I don't remember life before working on this film," said Ellar Coltrane, who was cast in Richard Linklater's Boyhood at the age of six and spent 12 years literally growing up on film.

A heartfelt musing on growing up and the passage of time, Boyhood follows the lives of Mason (Coltrane), his sister Samantha (Linklater's daughter Lorelei Linklater) and their parents (Ethan Hawke and Patricia Arquette).

Coltrane did not watch any footage of the film during the 12 years of shooting, and said it was "confronting" to finally watch himself age, haircut by haircut, growth spurt by growth spurt.

"It was a huge turning point in my life, seeing that for the first time. There was definitely a lot of emotion," he told ABC News Online.

"At first it was just about watching myself and seeing myself at all different ages. Now, it's easier to watch as a movie. There is something about seeing it all together in context that is comforting.

I'm sure if I wanted to get a face tattoo that might have been a problem.

Ellar Coltrane

"It is so beautiful and strange to now be showing it to people. It was part of my life for so long, it's become a part of me, so to be sharing it with people is very surreal."

Born in Austin, Texas, Coltrane was cast in the groundbreaking role in 2002, and said he has few memories of early filming.

"I really don't. There are a couple there but it's very strange, it's a huge part of my life that I don't remember," he said.

The now-19 year old said the film did not restrict his life, and he was free to experiment with clothes, haircuts and piercings, many of which which filtered through to Mason.

"But I'm sure if I wanted to get a face tattoo that might have been a problem," he joked.

"Richard always made sure he wasn't having me do something on screen that I hadn't done for the first time in real life.

"He would wait until I had a girlfriend before my character had his first kiss, for example."

Coltrane had high praise for the movie's "incredible" director, known for films including Dazed and Confused, Waking Life, School of Rock, Before Sunrise and its sequels and Bernie, which tells the story of a convicted killer who now lives in Linklater's garage.

"Richard has an incredible balance of very specific structure and incredible vision, where he knows very much what he wants and never wavers from that," Coltrane said.

"But he also is very open to collaboration and a constantly evolving, very organic way of telling stories."

That collaboration was evident when cast and crew members came together for a few weeks every summer, workshopping scripts before shooting that year's worth of scenes.

Like Coltrane, the cast members returned each year for shoots, though they were under no contractual obligation to do so.

Coltrane said the annual shoots "became like a reunion, like a summer camp".

"When you work with anybody you become bonded, but when you work with someone over the massive amount of time that we were spending, and just the type of intimate, emotional nature of the story, we became very much like family," he said.

There is something really comforting about having a story that is so intimate and tender but is just about the magic of the mundane.

Ellar Coltrane

"Not just the actors, but the crew too. A lot of the same crew members would come back year after year, even after they had moved to different jobs in different places, because they cared about the project and they wanted to be there.

"There was an incredible energy on set. It's really rare to be in an environment where everyone is there purely because they want to be there.

"No-one was making any kind of money, so it really was a labour of love.

"That kind of love makes a difference in what is shown on the screen."

He said it was a "blessing" to have enough time to become "lost" in the film, but noted that the enormity of the project did not fully dawn on him until he saw the completed project.

"For most of the project and most of the time working on the film, the end goal of it was so far away that I didn't think about it, it was just a life project that I was participating in," he said.

Coltrane said the beauty of the film is in its celebration of small, normal moments and how they define a person.

"I think so many of the stories these days are these set piece, dramatic moments that are supposed to define you as a person," he said.

"Real life's not like that. The soundtrack never really kicks in. There aren't cinematic cues to tell you when something is important — things just happen.

"There is something really comforting about having a story that is so intimate and tender but is just about the magic of the mundane."